WO 2016/012426 A1 discloses a method for three-dimensionally measuring a 3D aerial image of a lithography mask.
Methods for determining imaging aberration contributions in optical units with the aid of a speckle measurement are known from the technical articles “Off-axis Aberration Estimation in an EUV Microscope Using Natural Speckle” by Shanker et al., Imaging and Applied Optics Congress, USA 2016, the technical article “Quantitative phase retrieval with arbitrary pupil and illumination” by R. A. Claus et al., Optics Express Vol. 23, No. 20, published on Oct. 2, 2015 and the technical article “Aberration estimation using EUV mask roughness” by R. A. Claus, Extreme Ultraviolet (EUV) Lithography VI, ed. O. R. Wood I I et al. proc. of SPIE Vol. 9422, 942214.